This invention relates to a needle guide apparatus for discolysis procedures for the accurate insertion of an elongated injection needle into a select intervertebral disc for injection of a lysing agent or dye into the disc. The apparatus of this invention is particularly useful to aid chemonucleolysis procedures for non-surgical treatment of a herniated invertebral disc. The invention is of the type disclosed in the application of Robert Moore, entitled, "Needle Guide Apparatus for Discolysis Procedures" Ser. No. 744,392 filed, June 13, 1985 now U.S. Pat. No. 4,638,799.
As discussed in that application, certain chemicals have been discovered that dissolve nucleus pulposus material, the gelatinous substance within a vertebral disc. These agents, known generally as lysing agents, when injected into a herniated disc, cause the gelatinous material to dissolve, relieving pressure on nearby spinal nerves. Of the two principal applicable lysing agents, chymopapain and collagenase, chymopapain is used most frequently. Chymopapain is an enzyme derivative from papaya and has been found to dissolve the material forming the nucleus pulposus, without adverse affect on the surrounding annulus fibrosis or thin top and bottom plates of hyaline cartilage. Success from intradiscal injection of chymopapain has provided, in many cases, an effective alternative to open back surgery for removal of repair of a herniated disc by a laminectomy procedure.
A major problem with the chemonucleolysis procedures however, is the accurate placement of the needle into the nucleus pulposus of the herniated disc. Prior to the Moore apparatus needle placement was in part trial and error, often requiring up to one hour of a treating physician's time to locate the tip of the needle at the desired point within the disc. In addition to the tedium of the procedure and wasted time, misplacement or repeated perforation can be harmful to the patient. Prior devices to guide and locate the needle, as the device of the Moore reference, have been devised to direct the needle to the desired spot in the disc. Such devices, however, use complicated structures that in part restrict the angle options available to the surgeon. The needle guide of this invention expands the available angle option with a simplified structure using spherical vectoring techniques.
The improved needle guide is primarily used in discolysis procedures, but may be used in other procedures particularly where a substance is injected into a disc or other internal regions where both depth of penetration and direction of entry are critical.